SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7bfa9f8a782cf1236b51e5e0deda31d85cbd897db553747e466d90458ba5639' 
  AND token = '36qm62V8rndkHysozTFdRMJlcKs45inYiXUwfFZBvGw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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