SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a1fe6772b16f21d08dd84a0eef247f4eb81a2d5674633576cccf3d0f7af1365' 
  AND token = 'WX9uTxbQamYHEMwrmeLKdxK7yPitR6TMzjlT9NO0XyM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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