SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6684ed006fdfeaf43aa1dc568d3cfc860e70d660452c3352d67deb43bcca8ee' 
  AND token = 'yK5lv40b9sEgzIcnfgUNZPcxHy64w8CHGfpOIw545WQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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