SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '858493108cd8b61a5d1cdd327535e29bca1bd8d856df39d6f63425ffe7e363db' 
  AND token = 'fVercU8IUURo/XvNGSvwXaExYPgWqlssx2ldfqHMBRw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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