SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe351c5eaa66929443369748447104bf1bf88eba05f2adc911ee5b12b6ae0a04' 
  AND token = 'jb3XzvMr+iR/7nW69J+HniNHNjv+x6RmmnJv0f+s6qs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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