SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '979b421f0260e358704553fcf162177bbce3c6ee2c70e90f9d1eec42a75656d1' 
  AND token = 'mxnKYq6oTZFQo//fNvOqVg5/IxRvRqyf6s+HVVheTNM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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