SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5576794a9c2a1374f224b7828eed6c8480be3e8da0ce48e251f8e3860f3bed31' 
  AND token = 'I30/vP50uxIPqSDZASgphEmXSERKLTHW/VFdZvG2RgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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