SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c95a8b82878e98d427153ca58d36af599202ad2e92bba70f550a4f40a0240e9' 
  AND token = 'lNe91rjYtPKsaT1m/UmQWxMlVo6LuUcGM5uFqM7BxhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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