SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f473396c34aeba303e392a617364c35d201510eb3c1a4c02e4ee8fec4e1ad6f3' 
  AND token = 'bKGQusmjI7kxlRgebbwlFVFOHLSOOBkdMR0MlUX2gwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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