SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4788fdc8c36eec874865d5d02ac4204132fdce4b978fce471719f983ece12462' 
  AND token = '9Bz4LJG8hyq1XERVFuGiO9ano/IsTj845lcTLXUUZ50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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