SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '749113b58afc702f4bf3b929ea4b121f5aa06d167e82381e35eeb9a22122df84' 
  AND token = 'GqyrpNKgDQFjFfSCjU2dO8q3whQMjtTc5hbto3BmW2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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