SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1426d66db2b3b09b9ef20b79333d766700653c85f9c4cb4e2072a8a0a0998d80' 
  AND token = '6eCD4KJZbOELLcsWwS5WIPpbS7orId5aUZr5xKpdZk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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