SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a15bb6fdd374be7a7884fe9f4d0cb0efe51a40c56184818d67ee195da7b3179c' 
  AND token = 'yIZqcFGgQkrzN9t2taq+GIEtuBFyBqhOeEalNzLo89U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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