SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5214497fdbdd02a53d034388897dc576b6df91b48a75d906d3b223efe279609f' 
  AND token = 'XUNqybnd121ZxgJQCUGDvSgWYP5iKzWZvUNVe5HZeXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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