SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12e3b528a5cb267632a1189bc423060d9b7ee69d1990a1d2bc6aac16cd0b5eb9' 
  AND token = 'Z2jLPkVS0yR6ukhb4B5DTo9WYCVAV6vxrxAMFXaK8/E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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