SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f0c5f61bd72b8b51d78b89861070055024ad6d757f03f4106754537b7cea2e7' 
  AND token = '8IHw/UogLyn/AQAtFmzlQ4dMX0huE694ZejbI2tpImo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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