SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4847b4d36c6162133e7a3c6c37040acc8b53743a066f7825b5e63a1571fae2e1' 
  AND token = 'SYwm3G26hiR3dNAfXKOnOzvinAS7pFwXyQHbaty3p1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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