SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'f5f537bad8f35bd23f9ada4d1c879e53b494c476f6f269ae15c309740b4ecbfb' 
  AND token = '3iKFNFndiCLVc2VZg+/DzRjQAQcCqwOEolj8sf//b4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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