SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21516fb5f9c972e0194df489c422faa40d2e42b2bee9e3fc7c12eefa5cbf6047' 
  AND token = 'DXi/ayFxPKCLVNsJ/AQee/fDyEG1cT13biZEq1qGIVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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