SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94f34aef141a17fcc59346d879400a2b702896e05716bcb460206cb39143cae2' 
  AND token = 'EpNow5CwO/ccYGwpOxV286UckBLQrKiJ9qTqvnNpngE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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