SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '389df8819f2b99762c433f7ea7b73e8bccf4cb4ad426c8365f5f25d070b6de3d' 
  AND token = 'xB0nJndCYndOFjU0huBWZvKMBpv4BgoPgSaxI87KNSA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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