SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4269a36e6fdd135395da36aa7538daa162b71664abd39a80f79c2b053a2bfec' 
  AND token = 'l2Ex3K8k3FTWpscOcSxlC5wSeNudtF6D8uYWnP0OiBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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