SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3637e8836a1fb9e7294250fe46b2b3ccda0536b127962093f3050cd285b23b0' 
  AND token = 'mS3lCVr0Ze3elHjSgjOOUl4DmQxcMEhQuJxXL+d4PVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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