SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '473df51680bc25057a5fcd7797ff949a25e6dd1c2c4be235688f7e7c44d6533a' 
  AND token = 'qRYRHZdLq4LuO+ug7ckpfO1sXIEXQK465qzAotiGFB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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