SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eef7a16a60806c521f58acde9c450218a02250a7b3ed285b2f30015b5c8865a6' 
  AND token = 'KqPccKhxXVTaz+ybd+6ZDtamrzibvpGa/O3fhCaHFXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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