SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3b91f609f5c05b3cea33125360a8d41a3ec07941190846f8f6bd920f528a260b' 
  AND token = 'wHiCRPtXXujNEvhbsu0kkvc4Iy+aFZD/WkTTChwGtd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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