SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '53a6adac161fe5887e4d6d9ec75e599c8ee26888e34079abdb3da753408eebf4' 
  AND token = 'f397RN79pfXjdmvryW55lwSRsnmJoZxhv6XmCBYozAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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