SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36f1d02431704c56d10331170f74e5f191bcf5b3d987b4aa8b4b41aedd515890' 
  AND token = 'Dj323N2x4MXxYiGmxm1AlF/mjwM0LY0+trDJkfIBNf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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