SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08349f6c00e59fedac17274d0ccaec78f1bb6a916403fd2062a4c368a057c59d' 
  AND token = 'IBDfBwfntkAlaPI2xwTdZOhgNPEjt5IcOowfwTw08hw=' 
  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"
    }
  }
}