SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb846ae53958799a92109518c42969879312b7a7c86650b298950a7014c4633e' 
  AND token = '2vdXEsiyAoqaQDLwHIi8VkdTsOh01aiSdo2iVfdnh6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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