SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21a385316ad5fc556f9734acd388b597d5edee547faffc79df650d93a5f95f65' 
  AND token = 'q14zoZ/6uvEFvjFqehRqpShB6KeEPHqCx9YVGxIst6E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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