SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec6aec20fd6446cea12df19b729844a9f78af12af50752663287211d85b314b5' 
  AND token = 'pPn8zLsOZgJ409/+MXX0BcbCCkK98aOUgtxTxwFPyvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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