SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1ea246bd2fb85f564fe5fbf948e66221afb8a82a74a0a915cc572d7c9734284' 
  AND token = 'i+zC3vyKTWJX9VT/YGEFkVV5NjuM9+JXe9XACkVq3g0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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