SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a941aa9fa2a4fcb08b8f04b9afbf85d2721944860827fae2d6aa1d96f800cb39' 
  AND token = 'QdUrRDCwg+mbSkwnAGJFZKwD6TxOxVQRYhxUaqZZ3xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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