SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de99736092f26f0dab4f650d5338509255ecd43fe57e2a30580a42efe82632a5' 
  AND token = 'bRtb6IW1joLnxmZudcZ4Ck4Jg0ywwIpzyhpsKmfN4O8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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