SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dacf8848316f0d98fc32576e7d855d0e7971df0aedacbae913b4d5725f08c8f7' 
  AND token = 'tz5zq9ItQLtWs+GOKoy43ZHDqvJ8LgN4MD313VKVJi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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