SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '831a519617a862333c529816cf25cb55caebb5fc51f5f10a0f5843d0d577ac88' 
  AND token = '9OSBp0iVvLrIlSsaCl0mUexvJqwMLtx00qfYYgQVkHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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