SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fefbfe59ec84609ffc885fb347f882badf98a320f5d8544db250d7f54e0f4c75' 
  AND token = 'tgmhYxEpXHdlhA60hYKr4blUTlFPxfgVbo8tmYULYT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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