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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '151e242b554f203bb2baea76b606e2a386fe64ebcdec4f6ed3be3664b7b0d67b' 
  AND token = 'xQTPtPS1OIUwFUDUmHMLmNbch4lyNjYY5A9FyME+7ts=' 
  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"
    }
  }
}