SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbf19adcfe393a3b0f301f70e4d430d3549534d41d44a847e9ab0297cca81bcd' 
  AND token = '+1awbJ9ZvNTKF3KIWWIYWPhbK6wUIKWJZqGXpWsTug4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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