SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3db52a14dfb2c8c06474bbbaa5e2aa0689864b4deee7154a65122c7294caefaf' 
  AND token = '5/bckUIYpZrvyn1+e7ccSl55tCrkgm6MrwpuPuQddgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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