SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b81e7a9f9428f5670a8d3b841bb03dee71cad3e1a6b89344579ab7a728357252' 
  AND token = '8Qos+agJCVuDhIWhaYcldGb8M90JVrXtseTzg0O2Lbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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