SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfaadd7a420f1c718893567925a49068fd7dbc907cb121f7ac32103f3fec5c98' 
  AND token = 'w5xYtgWhKxPHJ6XqZ/CZrcKWtjWCE/IBQtLUIBYYQrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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