SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50643c7184d07d346ef603bc45411c046d5f27d590d989719473fdc6553578d8' 
  AND token = '7WYiA7o9K2gJOo77Npl5mEPZwXhzGZCrkw+Ofh+DJdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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