SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d9d9e969ddca02776eb75b0b60b0367060718a1152c2f03df39d62e4819fa2f' 
  AND token = 's4n3tj2wPVqtIJdiXiETmRgbdbhEbPCOv2kYy5lYbWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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