SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96d9e4d555ed7dbce18f34a204ca544c543b44aec6ef086efe906c0c8610b55a' 
  AND token = '41S8GytXdCCxy8mewVQmwBsi6ZJNABqyye0yZoh9mE0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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