SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0f7f8f2669a2739f64ea064bdc75722d09ac696b9fc1da457a403f7f1baf108' 
  AND token = '4sbHoGXLAP+Mu1uFqo8UpFnVlrwR/9lZ9kP+BG8vXhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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