SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad51b814272b5a840a6808af4b9247adace5a350fa8657972c56c8ed41636c78' 
  AND token = 'l04cbsnoQ0rNpgjpPIs659aGJrKd4zVLu4sABpRWsyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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