SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b39e8a8420706965522948ab38370aa941f5c1c73a46db0157c37911974ee7f' 
  AND token = '0/FYwU50mmQpkkN4eCvLPsYOG7/tag/JpVVgIKapbuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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