SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4b34e5df691ca517db8b10b5e668faa955a3bae521accf1d78e8cb40e974b8a' 
  AND token = 'T1RHWec4L+LIEAC0+36gcegaKfuFf7esNJ0T+/vbhOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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