SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6fdd42647f19addf445507e63f99524ceac44092b86f407d0b91a3af7fc57fe' 
  AND token = 'XqKgs72BGHKWtdCIG6Bdlb16deebxfCme7rKyS6erwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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