SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27dc31c90a5e78c533e75b286c4cbf8d2d1d22fb8b496ff9a49608a21bc79745' 
  AND token = 'v5Clcb9cIka6pz6xCU5OmzkPkHNn/FSRPhZ7sDYGgZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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