SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4ad5dadf5ad743e308466db37d7a1c94cdd3b2ecef2ba8fb3e7fc2846e7ac59' 
  AND token = 'JFvtKP1S3ZVFCs6gfxTYcCRu9DURfJWB/qY2NH0kjMw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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