SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '517a2dde622feb1fe803750a85148b2972944d5781fb8c316adf675ac1a00a96' 
  AND token = 'kssBqGpC3ZbnafLojDwTYjhoU1+yOerE7uWxjFdoYmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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