SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b035e9d31719b9fbf85295ace7195f8d7f9800214a0bee20fe85f48fe41639a3' 
  AND token = 'FkvUu4k9bUy3jVa1TXGy0aEzoPfAvhL80iada6t7EAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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