SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e68b4154f08ea31faa818df86094e5fc66fd00147a718b699800fde76cb97a1' 
  AND token = 'pgB87EErctpMnaNcPj7kUJWytTUHPtfAojUtbRkJ6V0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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