SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1db9a145fd32645e6515bbca732b7349157a495a26c7848f5f026c69f1b9412' 
  AND token = '6HdzNQECtP50ybdgKM1RAUmklxhdR6fzr88xKbFHqWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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