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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '321f4d1d39fd43fe32f60b9c8ff4ec9cfb5507ccf45890e7dc48b29d587cd0c2' 
  AND token = 'cpBg4NnPe/1+YK6K4eAx459vwKSe8AF6YX4QyV80bvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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