SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8db7f8290a33df2854dea6aa0b265cb055944c557157d447eb39012a5f827b76' 
  AND token = '3PBv+1RhLXR4UhU9mRVgyFOTpAFvEYg+r2BbarxC8eU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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