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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90ce533959e2b73f742aa4e342a9878d7e7911500d26a6bc54c13ca378d9a2a6' 
  AND token = 'iwZ9jOJsQTqEQ98/OhB+1tdoX6I4bP2k2PC3+6jngjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}