SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87ac73d8fb58268009105ada55591af7cceda61db0d221b837287b2d3c9ab421' 
  AND token = 'lRwnOHh62A/QwuMzF+TJjcXK1UPhr1/C5ibOIQZU1gY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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