SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f85010268d9d86467d125d20727f101607c7d44a730a42e8aa668250b40967' 
  AND token = 'xbf2vw5gkZWX07l17VUH+M4VZcDhrXw1OXNaaJcdtZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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