SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '978c56b1053ce519d15c54545bc4db02b1d089eeee115bc18788145af3b34076' 
  AND token = 'dVfpDXz+UnYa2Haawtt9TuAJaPLjLtpDdBGQVX43hvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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