SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49134d1f2f023bf6b3cbf0fd0542db0323a27a048d6765ba90dddc7b0a8ab617' 
  AND token = '8/XGthEwymQ6EC1o5Z774zbgYl4tF9khOhxJljsVsvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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