SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa8ea4ccc516b1e96a9f898dfa8836b55b2bcc00639dc4958cde12075bb05271' 
  AND token = '5aLvtARegRTlLIqeYmboTeWZ+RIH3t0duGwryjhvKbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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