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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2504ad6d2c70fc2c1166e6d4f353613d341391b36b0cf704d9acce4e3533ac34' 
  AND token = 'gXYJqeWxEu48ZRpiqb1e/GePfDHClFVeDrl6XrHpIWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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