SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc90b1de135d0a19ed5e13591e3ab78ceee45122755bd1786dab6e08342a57e0' 
  AND token = 'meRUsQ78YK+6/jD+K7ChVWaceBDPPGxnzaMeQtN3evI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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