SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '394e57987274a6f1d8029044e615879a961f16066fb010c728c11a60c5e8e085' 
  AND token = 'jPVI9vkx3zRHxpXZ9igXbsmYdvnWSNOnQS+8lTuphcc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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