SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0342b6f6e998b1a3125bc7830d7d51cef2f806d0e2b086ec7d32edfc4eb3e16b' 
  AND token = 'EM8qyhK6Q3hrTXKKpHOMH0qO7dSM+HUu3PI3BWojmHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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