SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a14841bb235a6941d395513b460d2727f1075bcdd312125ead0f620c707799db' 
  AND token = 'rcFwGIpqUhmXBBkOHXDZq4UVu6n4YWGtWFUD6jgFcHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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