SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '890f0948486ae5ceb56470117c504e90b6d7f0acf4107fc77f0252c01fdfe75f' 
  AND token = 'DkosCJidPmMpNzHDQf68KhFLKbxT5flAyXm/ZVjtCp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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