SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '494d8ec5c042948857162902ebbee172c0f32dbb6a85fed22a0b617859766741' 
  AND token = 'Uga/bH6aWFszeau7lc0mabus08MpQ7LrCxB2tH80X8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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