SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11f78e4c103f5913194672bf14ed55de3e36dce0684a7dd90dfe2edcdca8536f' 
  AND token = '6pXXu78sWCLBSmZlGwrMUOaLroLW5J6eSkIpqOCHWvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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