SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fa51a7211bf46349e3164412a558d25b3c73ba002be096c69a381e95ca87c53' 
  AND token = 'K5RP7AjlEpGY+wM3MG6IkC1AvxhbbW6hpObSvichDAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}