SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '830f269018b8314cfe543a80b024a8552e9992a845097250224ac4db43967e23' 
  AND token = 'kz3lmZw7/cM6ympBiz17qd3mqQy8zywYWrnWvl4MCbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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