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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28581a0f2e07056cdb2f8c6b3b55b9fded7db56d1f1ef6df3e7b5602529b35cd' 
  AND token = '4wt+n44xirWokWoD46VwkFdNhXkHlQwHY5Cxoxg+n0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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