SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b39f72c0c2a5179df40f9a06c72bb201af5db0dfbaf27dc706f6c003f88c064f' 
  AND token = 'CmSSyRE5OAiaBABBbk2wudHxJb7TeUuYSBjhux2cGfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}