SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21e98964856d85f1ed1604bd3f98ccad23d73e094aa126ecec88e92afb601b2b' 
  AND token = '+OdZWRFzVXngOj0LCaE92VKL7wgU8JWVc24hyq5NGDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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