SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6137a219579a925db405f2324272426a96ded575ec89b86678d52c772273294' 
  AND token = '89DV1RBMftpwIeCcvznJuvz55lEdT3lT/Jww9OZ51t4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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