SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12df9d27e1234dd754139241d25ed743decafa0c1626fe03d702b38692a75120' 
  AND token = 'k4ekpZ6POi3wbBfZDHtV23a9h8QiPxQSceyu3Ukp7L0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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