SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '793b39c6b586934782fb27cc21523a16ab8b566fc53f87a5824a0155506d2396' 
  AND token = 'EPKJGMhf7+Uo1OLxuWmPm3CmTtthrLigEts5OxXjwno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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