SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '393cc592e38039760e8af9c37ffee28d887d02eafd092468674b83a624b7b317' 
  AND token = 'Ao4WmutslBuuxnVvwGfUGP590Ec3v/CL5E6nB7QCAIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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