SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9314c300012528ba4c7897623eca7c41d5f83faa574efddbc67d3075b87543da' 
  AND token = 'jyYDR29czu/t+qiuOEGffUzGmuZbUZsTr0anRQaqmCA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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