SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '325b7ae2712a023e6e891160d73c40024b0eb7317a9337da1295cdacc327aea0' 
  AND token = '30py0j8FsPLdyAJpeFZXmgvolPUeiIQQPevtkZNli7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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