SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16d2085eecd44725f9a4a705d7f8749dd09eb6d809325d03370d973cd3516c21' 
  AND token = 'IhFbKHPubo/mvy+FoLS2kMpSmgMAWM2cixGYxETKAqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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