SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef6ba469795013efae654f7d781f60ae39fe49a0297a05b10eefb61414315615' 
  AND token = 'prPPzCCzkjpiGIw9YabF2AnFgPekfCpq8yYycFbQqAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}