SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1208cef7cc1c6e38402861d43ddd512f47f5034a46d0324fb1d262a23a3e3bae' 
  AND token = '2ywPNVoX+5b/XW70Kuz7gGzr/nAD0f5S8FpcgXQHGcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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