SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8383b20b058e59e785b3e7c37318aefcb07a75abaf939d6340fb920a5f3c385' 
  AND token = 'D+gk6Q53XtXplxkLIxjaRvAxXfgnwTOdEZ8fdHha/z8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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