SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96b6b50f621a290e5cb3ae8f9cb44401c3e2f4c3c48ecd95f54c4dfcecd4766b' 
  AND token = 'TRbJ7fbS3gwQvLncPyNmlA8ZHmTLKPJN7UYY6KjcvNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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