SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6a0a34974ea3f94db5b567531c8a53b292d3641cd89e69ab8bff2ade6d239c0' 
  AND token = 'gfhTR5uIvtrY7j3GROKU1x+/mVygBe5/OtDQcx+e/ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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