SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a43012d18936224358e16121d809da51bb4116fdd648df9a6c46d4bb6372642' 
  AND token = 'HKmw+WMA4p0w5SxVzXzIy/aqbgs+03XfnNBrq6wn3dY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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