SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6d2f3ebfa837a80d912983291145feefe3686313f17026db1d39f7e48ab594e' 
  AND token = 'RTWQpnqjqfYg1kUzhfMnZZN6fYNnS+IVeqPxHl8/Afs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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