SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '881d67a8fd4dc6a81ee0baaf790d19bc0a5f742a329279a1c3349f7bb3a4a08b' 
  AND token = 'oKjXZJp9Y0B4XWIrVVBDZqRjowUcdj2JgCbKUQItCko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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