SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1be343b97ba2cd027b5870056b62f6c457d7a03af3809cafd8f66c83aeab356' 
  AND token = 'KFHt2wfiWCwQRh02LwTZy0/pWhOWFkLFacKVQjF+t/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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