SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0ea793a760e437053afc800d87659f535e8d63f746e5ef0ebc6849201f135d' 
  AND token = 'v6UhxDI0iHjTBoWQYIeOUQngm+0NgzNUQ3BppIGywWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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