SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e788dae9033da7da9c1b58069efd57661313339e4291879d9674f65a69058a85' 
  AND token = '2UEs92hwApjNHutTuUyv+zvzj2cn5ShfCVaPkl5DFow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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