SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b040702a7884a6c92c427e796245242b2e480c2679315531e016447533b78e5d' 
  AND token = 'AGh54hCdZpS+7VVHA6Wz0ZkUwbXw/w36bKjTIjYg0+I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}