SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '578dadf61650ed31cd45cc90ed04374f38c212ecdcc65503cbb82756478dbc4e' 
  AND token = 'GWuaUAtJuQ2iGsiPappBWsBUYUSQxxVGTYKQ/MMsZ+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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