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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fb3ec9fd5818f2350e0a456324b2cfbba8ddf210e1420ccabd0da722935cbe5' 
  AND token = 'UN1YFKc7iOkCUQDIOrAld/fUVDjADKmBdN6ChbYmqO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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