SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5be0275e76c42a5561d7dd95c0935dd2f9bd92819d92c626f37e86e87ba7544' 
  AND token = '5MHAQ+hT6qqtd7BcirXOxXcIhvyE54AN9eXAVcagCXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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