SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19923faa9307953ebcf0c313742e018ebc7f5d747127c1d9824d7d7d77a1a252' 
  AND token = 'cv9jav78IgDhIKQMiH8dhghy8BfdZlzinOmEYOsrBa8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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