SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bb6614104712fd4f0677dabc5db2af94035d97b6a2fe6d58509385fd824f425' 
  AND token = 'ZHrNcjcgqAOgZn59Km+L9fwf0UfVdqfPVT/jJSHVquo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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