SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ff69442cb5c0b45781213dbe6b23615cb1fe317d8701b8a3eb49336a3539321' 
  AND token = 'T+ctItyk3qoF/wEZrafe0jId7sq7rd/trmPxLsIjLMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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