SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18047dca1a401d35387c44ddc3628ee20608f741f04b7670ef052988d17cdfcb' 
  AND token = 'XE2rQo32psnVlkEBCf03egI6l6foMQixdncZLUS3axc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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