SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd6b3eb9651626a1d3a37d9a2c8f2ea646036119854bcddad4252a735f1d7ff80' 
  AND token = 'uB6m5hNMHGaQK1BWWl+OO2Dyx+c8Ue8nVc7j4KCLU2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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