SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a9aeb2686abfd997585b07eb7a1a38540eeb89d031234642b2b8d9b2d737c7' 
  AND token = 'QVu8ue+qPUdjwqDxlETHYUmPe8WGIQH4JNaCDFUfz5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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