SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f3f7973df01c9ad4e4a8736adcfffe25974af179b9a612cc112340c9eab51ff' 
  AND token = 'ThlYirvueaBpVnGfQjrXuzIf/hc90HgDVWFIshxPdKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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