SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db86e6b8f81a61f878d97f56fce60b03aa0e029200402aa98633381f7b184acc' 
  AND token = 'C4sKu+emOkomRqbdTpcsPC2yj3nzmLz2wZr131WhbmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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