SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '7991172211677ae43d819a14a4ae8c27326ab8523ac3c14d118fd55c0ac4a072' 
  AND token = 'HKOrhMrDRjz/OpfVSGXuFXeE5jRdVELSrKINYv7FUwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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