SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fae0c27821ea2e9682d44270452f574379d85afab2d72ca6db04a8338c3f90f' 
  AND token = 'MgATmYVDPtZl/X7rwHSx+NcJ8GZWp9svyrAmvZ/9cIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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