SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27144e0a232419d155c163333d2b4818804e25046b274e6330d9bdc36d0584fa' 
  AND token = '5+WpqTkZB98yHMyLZSEihQDkx4PU1JKwhpnxnlukZPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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