SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00e6723195de39ff96563b654b72bdfa47a2991a771e7db962836285e535ea47' 
  AND token = 'DMLAry+814FG+HaPgKqmU3Du6HN4wV86pTP57FlKTGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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