SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a3c70e3b767e09544127621b684982672c41b8bf6043c803f428c7918fdbb14' 
  AND token = 'AjwtlUSE03nHOnxFjif5PwztaNGkTeMIwPoHNlIqVWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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