SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f7291d59ec85927ae925b5509df85740c8eb8158b77cb19673b41f099306b9' 
  AND token = 'F+ZmBNLpZ6ntqSeCIERDEY0TaXLLAyebAL5N23SHl3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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