SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5000e28aadb0660bebfb49f8e694ab7d62ba326111ede9ee675b06910e371e9' 
  AND token = 'oeH3UIpwsUsOWmbR6p8Cm5hPaZmiQsDDKvTJWIlZYfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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