SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e438fada1143d18acc39b2d532df5b4a3ffc7be812f69adb858b0b2101891b03' 
  AND token = 'k0PlyTKlVgHbjTSRYm/ubmPFsthl+UfeyvvXjWXOerE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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