SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c50ab369ae0d0302d504613956cbcbcac831991ab6726560ca1a4c815fbc5fe2' 
  AND token = 'NnTJJ/n0TQWjtfc5FLboU75GsO7lBetc+SiW+ybyaXM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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