SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a350f80de1c68250f49a7efc52772fe154f9761f69337875039abe4841779e11' 
  AND token = 'gNvAlRlm2btgT2CPf5YrIUd/bhbYZhvivzuKEjBqtCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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