SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5de3187fb7e81858f5b1923acab57a5fa3bf3854fabc7373b1720cec0e9689d' 
  AND token = 'rg+ozFP2YpkkgBL8UAvQXWbebtEbEDhMG+TogCaAInM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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