SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f77725090bacda6263c664d30adcc739de0f298a09768775fac1dda283197c4' 
  AND token = 'LzY/hAfnnv1s3G7isdd+AzDhPtEZnS9MQx12B3wSvuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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