SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf25793144d4b2ad1385d103771ef3e5f788f1bcacaa4193fb8f5ef6fa520a4e' 
  AND token = 'R81RVmq8bgJ7KiIuTTBR/+BG5c28BAf6lKjdBicbPiI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}