SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '431a5905b558cd506f353530796e8e6f99e1f691bf2585d65c213dbfd656cde3' 
  AND token = 'Pazz2LUckxAp72dvmVpLXwwBIJwLCBMZo5XMriUQ+1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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